C-C One-Electron σ-Bond Analysis
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Questions and Answers

What is the primary focus concerning molecules with a C-C one-electron σ-bond?

  • Studying their thermal properties
  • Determining their optimal synthesis method
  • Achieving energy reversal between HOMO and SOMO states (correct)
  • Evaluating their stability under different conditions

    • What condition is stated regarding the comparison of E1ox and E2ox in the proposed redox mechanisms?

  • E1ox is always lower than E2ox
  • E2ox is always higher than E1ox
  • E1ox is always equal to E2ox
  • E1ox is greater than E2ox in some cases (correct)

    • Which statement accurately reflects the challenges mentioned in the research?

  • Reports on the desired molecules are extensive
  • Optimal approaches for energy reversal remain elusive (correct)
  • Energy reversal mechanisms are well understood
  • Radical cation states have been thoroughly studied

    • What role do the HOMO and SOMO states play in the described energy reversal?

    <p>They are crucial for understanding redox mechanisms</p> Signup and view all the answers

    In the context of the research, what does degradation refer to?

    <p>The loss of stability in a compound</p> Signup and view all the answers

    What is implied about the research environment based on the affiliations listed?

    <p>Collaboration occurs between multiple universities</p> Signup and view all the answers

    Which of the following is a likely next step in the research according to the content?

    <p>Identifying the exact conditions for energy reversal</p> Signup and view all the answers

    What conclusion can be drawn about the ability to study HPE derivatives based on the content?

    <p>Understanding their redox mechanisms is complex</p> Signup and view all the answers

    What type of electron transfer is discussed in relation to 3,6-diaryl-2,6-octadienes?

    <p>Photoinduced electron transfer</p> Signup and view all the answers

    Which chemical species is highlighted for its divergent reactivity based on electron-transfer conditions?

    <p>1,3-Bis(4-methoxyphenyl)cyclohexane-1,3-diyl cation radical</p> Signup and view all the answers

    What notable product formation is mentioned in relation to the rearrangements of the diketene compounds?

    <p>Formation of bicyclo[2.2.0]hexane derivatives</p> Signup and view all the answers

    Which method was confirmed by X-ray crystallography as mentioned in the document?

    <p>The B⋅B one-electron σ bond</p> Signup and view all the answers

    Which year was the study on triphenylmethyl published in the Journal of the American Chemical Society?

    <p>1900</p> Signup and view all the answers

    What is the chemical characteristic of hexaphenylethane associated with strains?

    <p>Ultralong C–C bond</p> Signup and view all the answers

    Which concept relates to the isolation of a benzene valence isomer as per the document?

    <p>One-electron phosphorus–carbon bonds</p> Signup and view all the answers

    What type of chemical bond did Suzuki et al. focus on in their study related to ultralong C–C bonds?

    <p>Bi-electron molecular bond</p> Signup and view all the answers

    What initial substance was combined with iodine in the synthesis of dication salt 12+(I3−)2?

    <p>A 3.00 mg compound labeled as 1</p> Signup and view all the answers

    What was the temperature maintained during the stirring process in the synthesis?

    <p>26 °C</p> Signup and view all the answers

    What was the result after drying the resulting suspension of the synthesis?

    <p>A dark violet solid</p> Signup and view all the answers

    What method was used for chromatography in the synthesis process?

    <p>Column chromatography on silica gel</p> Signup and view all the answers

    What indication is given regarding the 1H NMR spectrum recorded during the synthesis?

    <p>It was silent due to a radical cation's presence</p> Signup and view all the answers

    What was the melting point range recorded for the synthesized solid?

    <p>177–182 °C</p> Signup and view all the answers

    What precursor was used to dry the acetonitrile before use in the experiment?

    <p>Calcium hydride</p> Signup and view all the answers

    Which analytical technique was employed to record the 13C NMR spectra?

    <p>BRUKER Ascend 400 spectrometer</p> Signup and view all the answers

    What parameter is notable about the Csp3–Csp3 single bond in HPE 1?

    <p>It has the highest bond length among HPEs.</p> Signup and view all the answers

    Which structural feature of HPE 1 contributes to its oxidation process?

    <p>Rigid acenaphthylene core.</p> Signup and view all the answers

    What is the observed oxidation potential of the first step in the oxidation process of HPE 1?

    <p>+0.57 V</p> Signup and view all the answers

    What is a significant difference between the structures of 1 + and 12+?

    <p>The geometrical difference is reproducible.</p> Signup and view all the answers

    For how long can crystals of 1 +I3− be stored under ambient conditions without decomposition?

    <p>At least two weeks.</p> Signup and view all the answers

    What is the primary reason the naphthalene core does not facilitate stepwise oxidation in HPEs?

    <p>It does not promote bond elongation.</p> Signup and view all the answers

    What does the bond length of the C…C distance in HPE 1 indicate?

    <p>It is suitable for a one-electron bond.</p> Signup and view all the answers

    What is indicated by the R indices (R1 and wR2) mentioned in relation to HPE 1?

    <p>They relate to the crystallographic quality of the structure.</p> Signup and view all the answers

    What occurs at 110 K in relation to compound 1?

    <p>X-ray analysis of 1 + I3−</p> Signup and view all the answers

    What is the bond length of the C C one-electron σ-bond?

    <p>2.921(3) Å</p> Signup and view all the answers

    Which of the following statements is true regarding the structural parameters?

    <p>Thermal ellipsoids are displayed at 50% probability.</p> Signup and view all the answers

    What was the core structure of the B B one-electron bond based on?

    <p>Naphthalene core</p> Signup and view all the answers

    What does the difference in interatomic distances suggest?

    <p>Rigidity of the π-framework</p> Signup and view all the answers

    What wavenumber (cm–1) corresponds to the C C symmetric vibration?

    <p>390 cm–1</p> Signup and view all the answers

    What is observed at around 100 K related to the structural analysis?

    <p>X-ray analysis of 1 2+(I3−)2</p> Signup and view all the answers

    The experimental data for Raman intensity is shown as a function of which parameter?

    <p>Wavenumber (cm–1)</p> Signup and view all the answers

    Which aspect of the structure of 1 2+(I3−)2 is omitted for clarity?

    <p>I3− anion</p> Signup and view all the answers

    What is noted about the thermal behavior of compounds at different temperatures?

    <p>Phase transitions exhibit discontinuous changes</p> Signup and view all the answers

    What does the presence of disordered thermal ellipsoids indicate?

    <p>Variability in atomic positions</p> Signup and view all the answers

    Which experimental method is used to analyze the structures mentioned?

    <p>X-ray crystallography</p> Signup and view all the answers

    What condition is NOT stated about the analysis conducted at 100 K?

    <p>Behavior under high vacuum</p> Signup and view all the answers

    What is indicated by the presence of the vibrational peak at 379 cm–1?

    <p>Presence of molecular vibrations</p> Signup and view all the answers

    Study Notes

    C-C One-Electron σ-Bond

    • Molecules with a C-C one-electron σ-bond are elusive due to the difficulty of achieving an optimal energy reversal between the HOMO of the neutral state and the SOMO of the radical cation state.
    • Electron-donating heteroatoms can help achieve this energy reversal.

    HPE 1 Structure

    • HPE 1, a molecule with two spiro-dibenzocycloheptatriene (DBCHT) units, has an elongated Csp3-Csp3 single bond (1.806(2) Å at 400 K).
    • This elongated bond increases the HOMO level and results in a stepwise oxidation process.

    X-ray Analysis of HPE 1

    • X-ray analysis of HPE 1 revealed an unsymmetrical bent-planar structure with a C-C one-electron σ-bond with a bond length of 2.921(3) Å.
    • The structure deviates from the typical planar conformation of a pimer composed of cationic and radical moieties or molecules.
    • The observed structural difference is intrinsic and reproducible, confirmed by analyzing several single crystals of HPE 1 and its dication.

    Raman Spectroscopy

    • Raman spectroscopy confirms the presence of the C-C one-electron σ-bond by detecting a vibrational mode at 379 cm-1.
    • This mode represents the symmetric vibration of the C-C one-electron σ-bond.

    Synthesis of Dication Salt 12+(I3-)2

    • Dication salt 12+(I3-)2 is synthesized by reacting HPE 1 with iodine in dry CH2Cl2.
    • The resulting suspension is dried under reduced pressure to yield a dark violet solid.

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    Direct Evidence for a Carbon-Carbon One-Electron σ-Bond PDF

    Description

    This quiz explores the intricate details of C-C one-electron σ-bonds and their significance in molecular structures like HPE 1. It covers topics such as energy reversal in radical cations, the effects of heteroatoms, and the structural findings from X-ray analysis. Test your understanding of these complex concepts in molecular chemistry.

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